YOU SAID:

i'm using the computer to write a letter to my grandfather whose name i cannot say here.

INTO JAPANESE

私はここでは言えない名前の私の祖父に手紙を書くためにコンピューターを使っています。

BACK INTO ENGLISH

I use a computer to write to my grandfather whose name I can not say here.

INTO JAPANESE

私はここで言うことができない名前の私の祖父に書くのにコンピュータを使います。

BACK INTO ENGLISH

I use a computer to write to my grandfather whose name I can not say here.